Effectiveness of egg yolk immunoglobulin against the intracellular salmonid pathogen Piscirickettsia salmonis.

AIMS: To produce and characterize egg yolk immunoglobulin (IgY) against the fish intracellular pathogen Piscirickettsia salmonis as well as to evaluate the antibacterial activity of IgY in vitro and the availability in the serum of fish immunized orally. METHODS AND RESULTS: Specific IgY was produced by immunizing hens with P. salmonis proteins. The IgY was obtained from egg yolks using the ammonium sulphate precipitation method and it was characterized by SDS-PAGE, Western-blot and ELISA, demonstrating that anti-P. salmonis IgY strongly reacted specifically against P. salmonis proteins. In an in vitro neutralization assay, IgY inhibited the growth of P. salmonis in liquid medium at concentrations ranging from 128 to 256 µg ml(-1) in a dose-dependent manner. Interestingly, IgY against P. salmonis also generates a strong protective effect on the infection of P. salmonis in salmon head kidney-1 cells. In addition, the bacteriostatic function of IgY appears to result possibly from agglutination by the interaction of IgY with surface components of the pathogen. Finally, to confirm this IgY as an alternative for salmonid treatment, Atlantic salmon (Salmo salar) specimens were orally inoculated with IgY. The analysis of the sera demonstrates that IgY was effectively transported by fish intestine and that this immunoglobulins maintains its properties and recognizes several proteins of P. salmonis up to 12 h after inoculation of IgY against P. salmonis. CONCLUSIONS: Specific IgY effectively inhibited the growth of P. salmonis and this immunoglobulin can be released in the Atlantic salmon sera when administered orally to fish. SIGNIFICANCE AND IMPACT OF THE STUDY: We propose that this specific IgY against this fastidious micro-organism could be a useful strategy for the treatment of piscirickettsiosis.

Embarazo cornual: tratamiento médico con dosis única de metotrexato / Cornual pregnancy treated with single intramuscular methotrexate dose

Presentamos un caso de embarazo cornual o intersticial diagnosticado en forma precoz a través de ecografía transvaginal, tratado exitosamente, en forma conservadora, con dosis única sistémica de metotrexato.

We present a case of cornual or interstitial pregnancy diagnosed during early stage through transvaginal ultrasound, treated successfully with single systemic intramuscular methotrexate dose.

Mioma primario de la trompa de Falopio: una localización muy infrecuente / Primary myoma of the fallopian tube

Presentamos un caso muy poco frecuente de mioma extrauterino, localizado en la trompa de Falopio derecha, en su porción media. A la inspección y anatomía patológica, no se encontraron evidencias de dependencia alguna con el útero. Constituyó un hallazgo en una mujer sometida a cirugía abdomino-pélvica debido a infertilidad primaria y dolor abdominal derecho. Los estudios previos con ultrasonido identificaron una imagen compatible con un mioma subseroso grande y pediculado...

We present a rare case of extrauterine fibroid, located in the right fallopian tube in middle portion. The inspection and pathological study not found evidences of any dependence with uterus. It was a finding in a woman undergoing abdominal-pelvic surgery because of a primary infertility and right abdominal pain. Previous studies with ultrasound identified an image support a large pedicle subserous myoma...

Peripheral facial nerve lesions induce changes in the firing properties of primary motor cortex layer 5 pyramidal cells.

Facial nerve lesions elicit long-lasting changes in vibrissal primary motor cortex (M1) muscular representation in rodents. Reorganization of cortical representation has been attributed to potentiation of preexisting horizontal connections coming from neighboring muscle representation. However, changes in layer 5 pyramidal neuron activity induced by facial nerve lesion have not yet been explored. To do so, the effect of irreversible facial nerve injury on electrophysiological properties of layer 5 pyramidal neurons was characterized. Twenty-four adult male Wistar rats were randomly subjected to two experimental treatments: either surgical transection of mandibular and buccal branches of the facial nerve (n=18) or sham surgery (n=6). Unitary and population activity of vibrissal M1 layer 5 pyramidal neurons recorded in vivo under general anesthesia was compared between sham-operated and facial nerve-injured animals. Injured animals were allowed either one (n=6), three (n=6), or five (n=6) weeks recovery before recording in order to characterize the evolution of changes in electrophysiological activity. As compared to control, facial nerve-injured animals displayed the following sustained and significant changes in spontaneous activity: increased basal firing frequency, decreased spike-associated local field oscillation amplitude, and decreased spontaneous theta burst firing frequency. Significant changes in evoked-activity with whisker pad stimulation included: increased short latency population spike amplitude, decreased long latency population oscillations amplitude and frequency, and decreased peak frequency during evoked single-unit burst firing. Taken together, such changes demonstrate that peripheral facial nerve lesions induce robust and sustained changes of layer 5 pyramidal neurons in vibrissal motor cortex.

Mechanisms underlying the inhibition of the cytochrome P450 system by copper ions.

Copper toxicity has been associated to the capacity of free copper ions to catalyze the production of superoxide anion and hydroxyl radical, reactive species that modify the structure and/or function of biomolecules. In addition, nonspecific Cu2+-binding to thiol enzymes, which modifies their catalytic activities, has been reported. Cytochrome P450 (CYP450) monooxygenase is a thiol protein that binds substrates in the first and limiting step of CYP450 system catalytic cycle, necessary for the metabolism of lipophilic xenobiotics. Therefore, copper ions have the potential to oxidize and bind to cysteinyl residues of this monooxygenase, altering the CYP450 system activity. To test this postulate, we studied the effect of Cu2+ alone and Cu2+/ascorbate in rat liver microsomes, to independently evaluate its nonspecific binding and its pro-oxidant effects, respectively. We assessed these effects on the absorbance spectrum of the monooxygenase, as a measure of structural damage, and p-nitroanisole O-demethylating activity of CYP450 system, as a marker of functional impairment. Data obtained indicate that Cu2+ could both oxidize and bind to some amino acid residues of the CYP450 monooxygenase but not to its heme group. The differences observed between the effects of Cu2+ and Cu2+/ascorbate show that both mechanisms are involved in the catalytic activity inhibition of CYP450 system by copper ions. The significance of these findings on the pharmacokinetics and pharmacodynamics of drugs is discussed.

Manejo laparoscópico de quistes ováricos complicados o persistentes durante el embarazo / Laparoscopic management of complicated or persistent adnexal cysts during pregnancy

Antecedentes: El incremento en el hallazgo de quistes anexiales durante el embarazo sería el mayor uso de técnicas de reproducción asistida con hiperestimulación ovárica controlada. La complicación más frecuente sigue siendo la torsión anexial. Objetivo: Revisar el manejo de quistes anexiales complicados o persistentes, durante el embarazo, con resolución laparoscópica. Método: Revisión retrospectiva de 9 pacientes consecutivas, ingresadas al Departamento de Obstetricia y Ginecología Clínica Las Condes. Resultados: La edad gestacional de ingreso fue entre 5+5 y 27 semanas. Cinco casos fueron producto de fertilización asistida y cuatro espontáneos. Ocho (85,6 por ciento) embarazadas, ingresaron por dolor abdominal agudo. Otro caso ingresó a cirugía electiva por quiste ovárico persistente. Los quistes tenían entre 6 y 13 cm. En 5 se realizó sólo destorsión ovárica, en 1 ooforectomía y en 1 quistectomía. Se realizó punción, destorsión y fijación a ligamento útero ovárico, bilateral, en la otra paciente. Se registró un caso de fiebre en el postoperatorio. El alta hospitalaria fue a las 48 horas en 6 (67 por ciento), a las 72 en 2 y a las 96 en 1. El estudio biópsico diferido en 3 pacientes demostró: 1 quiste seroso paratubario, 1 quiste luteínico parcialmente hemorrágico y 1 infarto anexial. Todos los embarazos evolucionaron normalmente. Conclusión: Nuestra experiencia confirma que en el embarazo la laparoscopía es una buena opción al requerir una cirugía por quiste anexial complicado o persistente.

Background: Recent reviews show an increase in the finding of adnexal cysts during pregnancy. One reason could be the use of assisted reproductive techniques with controlled ovarian hyperstimulation. Objective: To review the experience in managing via laparoscopy complicated or persistent adnexal cysts during pregnancy. Method: Retrospective review of 9 consecutive patients, admitted at the Department of Obstetrics and Gynecology, Clínica Las Condes. Results: The gestational age was between 5+5 and 27 weeks. Five were the product of assisted fertilization and four spontaneous. Eight (85.6 percent) pregnant women were admitted by emergency room because of acute abdominal pain and another one went through elective surgery for persistent ovarian cyst. Preoperative diagnosis of the 8 patients admitted by emergency: adnexal cyst complicated with torsion in 6 (1 adnexal infarction) and 2 cases of acute abdomen. The cysts were between 6 and 13 cm. Type of surgery: in 5, only distortion; ovarian oophorectomy in 1 and cystectomy in one. Puncture, detorsión and bilateral fixation of uterine ovarian ligament, in another patient. One case required conversion to laparotomy with adnexectomy. Postoperative fever was observed in one patient. Discharge was at 48 hrs in 6 (67 percent) cases, at 72 hrs. in 2 and 96 hrs. in 1. Deferred biopsy performed in 3 patients showed: paratu-barian serous cyst, partially hemorrhagic luteal cyst, adnexal infarction. All pregnancies went on normally. Premature births are not reported. Conclusion: Our experience suggests that laparoscopic approach is a valid option for complicated or persistent adnexal cysts in pregnant women.

Immunosuppression with generic tacrolimus and mycophenolate mofetil in renal transplant recipients: preliminary report in Chile.

The association of tacrolimus (TAC) and mycophenolate mofetil (MMF) in renal transplant patients has diminished the incidence of acute rejection. We evaluated the use of generic TAC and MMF as primary immunosuppression in 6 living related (LR) and 11 cadaveric (C) donor renal transplant recipients (9 men, 8 women) of mean age 37 +/- 12 years (range, 17-56 years) between May 2006 and June 2007. From day 0 all patients received TAC, MMF, and prednisone without antibody induction. They were followed for the development of acute rejection, graft loss, side effects, and mortality. Mean follow-up was 7.6 months (range, 2-15 months). No biopsy-proven acute rejection episodes, graft loss, or recipient deaths were observed. Creatinine levels at the end of the study were 1.90 +/- 1.0 mg/dL (range, 0.62-4.25 mg/dL for C recipients and 1.19 +/- 0.15 mg/dL (range, 0.91-1.35 mg/dL) for LR recipients. Mean systolic and diastolic blood pressures were 130/73 mm Hg with 12 patients (70.5%) on antihypertensive therapy with calcium antagonists and beta-blockers. Mean (range) of total cholesterol, triglycerides, and glucose were 172 (110-244) mg/dL, 139 (69-277) mg/dL, and 89 (63-129) mg/dL, respectively. MMF was suspended in 1 patient due to diarrhea and 1 other because of leukopenia. We observed that generic TAC and MMF yielded effective and safe immunosuppression in terms of mortality, biopsy-proven acute rejection, and graft loss with a low incidence of adverse effects during the study period.

Endometrioma de músculo recto abdominal en paciente con cicatriz de cesárea / Abdominal wall endometriosis in a patient with caesarean section scar

La pesquisa de un nodulo en la pared abdominal, en una paciente con antecedente de cirugía ginecológica u obstétrica, debe considerar un posible endometrioma. La anamnesis y la ecografía, son los elementos principales, en la hipótesis diagnóstica. La punción y aspiración con aguja fina puede considerarse entre los exámenes pre-operatorios. El tratamiento es quirúrgico y consiste en una resección completa del tumor, lo que nos permitirá a través del estudio histológico, la confirmación diagnóstica, ante la presencia de glándulas endometriales. Para disminuir la posibilidad de recidiva, se debe realizar una resección con márgenes amplios. Presentamos un caso de endometrioma de músculo recto abdominal, en una paciente con antecedente de cesárea 2 años previos. Revisamos el diagnóstico diferencial, los métodos de aproximación diagnóstica y el tratamiento.

The finding of an abdominal wall nodule in a patient with a history of gynecological or obstetrical surgery, must consider possible endometrioma. The anamnesis and ultrasound are the main elements in the diagnostic hypothesis. Fine needle aspiration cytology can be considered in the preoperative evaluations. The treatment is surgical and consists of a complete resection, with histopathological study to confirm the diagnosis, when the endometrial glands are observed. In order to diminish or avoid recurrence, resection must be performed with wide margins. We present a case of abdominal wall endometrioma in the rectus abdomis muscles, in a patient with caesarean section scar two years before. We review the differential diagnosis in an abdominal wall mass, the diagnostic approach methods and the treatment.

Torsión anexial y embarazo: resolución laparoscópica mínimamente invasiva, con entrada bajo visión directa / Adnexal cyst and pregnancy: laparoscopic management

Las masas anexiales durante el embarazo son de baja frecuencia, sin embargo tienen una alta probabilidad de complicarse, produciéndose torsión hasta en un 25 por ciento de ellas. Ante la necesidad de una resolución quirúrgica, debemos tener en cuanta los riesgos de desencadenar una pérdida fetal, como resultado de una cirugía muy invasiva. Gracias a los avances tecnológicos, el mayor conocimiento y manejo de anestesia durante el embarazo, la laparoscopia debería constituir la mejor vía para realizar estas cirugías. De esta forma, se aplican todos los principios de mínima invasión, facilitando un menor daño y rápida recuperación, con poca probabilidad de afectar el embarazo. Presentamos un caso de quiste anexial complicado con torsión, durante el segundo trimestre del embarazo, resuelto por medio de cirugía laparoscópica, con entrada bajo visión directa con cámara, para reducir la posibilidad de daño uterino.

The adnexal masses during pregnancy are of low frequency; nevertheless they have a high probability of complication. The torsion can be observed in a 25 percent of them. When they need surgery, we must be aware of the risks and morbidity imposed to the fetus and the patient. The technological advance and best knowledge of fetal physiology and hemodynamics plus anesthesia during the pregnancy, allow that laparoscopy constitutes the best via to perform this surgery. By the way, all principles of minor invasion are applied, with short hospital stay and lesser morbidity affecting the pregnancy. We present a case of a complicated adnexal cyst, with torsion, during the second trimester of the pregnancy. A laparoscopic surgery was performed, with entrance under direct camera vision, to reduce uterine damage.

Therapeutic drug monitoring of mycophenolic acid in kidney transplant patients: a abbreviated sampling strategy.

Mycophenolic acid (MPA) levels have demonstrated a good correlation with clinical outcomes, but with great pharmacokinetic variability between patients. Therapeutic drug monitoring (TDM) is recommended to include a 12-hour area under the concentration-time curve (AUC). Since full AUC estimates are not practical for routine monitoring, limited sampling strategies have been suggested. We evaluated MPA pharmacokinetics in 18 stable renal transplant patients receiving mycophenolate mofetil (MMF) as part of their immunosuppressive therapy. The correlation between measured and estimated AUC was assessed using 4 different sparse sampling algorithms. The mean values for C(0) and AUC(0-6h) were 1.8 +/- 1.2 mg/L and 31.1 +/- 14.8 mg*h/L, respectively. The dose-corrected AUC(0-6h) was 35.4 +/- 17.9 mg*h/L. Regarding the single time points, C(0) showed a low correlation with AUC(0-6h) (r(2) = .34); C(1.5), the best correlation (r(2) = .72); and C(3), the worst (r(2) = .07). Sparse sample algorithms used to estimate 12-hour AUC including C(0), C(1), C(2), C(3), C(4), and/or C(6) showed a good correlation with the calculated AUC(0-6) (r(2) = .81-.96). The algorithm that used C(0), C(1), C(2), and C(4) showed the best correlation, but we also found a good correlation (r(2) = .91) with C(0), C(1), and C(2). Based on these results, we have suggested using the 3-point algorithm (C(0), C(1), and C(2)) for MPA TDM in stable renal transplant patients due to the good correlation with drug exposure and better functionality than an algorithm using a 4-hour postdose measurement.

Tratamiento médico del embarazo ectópico: evaluación prospectiva de la fertilidad / Medical treatment of ectopic pregnancy: prospective evaluation of fertility

Se presenta la evaluación reproductiva, a través del método de las tablas de vida, aplicado a una cohorte de 16 pacientes tratadas con metotrexato parenteral por embarazo ectópico, en el período comprendido entre julio de 1993 y julio de 2002. Estudio realizado en el Instituto de Investigaciones Materno-Infatil, Universidad de Chile y Servicio de Ginecología. Hospital San Borja-Arriarán e Integramédica, división Ginecología. Todas las pacientes negativizaron la gonadotrofina coriónica. La permeabilidad tubaria fue evaluada en 12 de 16 pacientes, siendo permeable la trompa ipsilateral en 75% de los casos. La tasa acumulativa de embarazo intrauterino a los 24 meses fue de un 57%, con una fecundabilidad de 2%. En los casos con trompa única, la tasa acumulativa de embarazo normal fue de 40%, con una fecundabilidad de 1,6% a los dos años. Al evaluar la recidiva de embarazo ectópico, encontramos una tasa acumulativa de 48% a los 24 meses. Los resultados obtenidos en esta serie en términos de permeabilidad tubaria y embarazo intrauterino son satisfactorios. La recidiva de embarazo ectópico y la baja fecundabilidad se asociarían al daño tubario previo. El tratamiento médico del embarazo ectópico es una alternativa válida en casos bien seleccionados, con resultados reproductivos aceptables.

Our group performed a survival analysis of fertility after pregnancy of 16 patients treated with intramuscular methotrexate, between july 1993 and july 2002, in the Instituto de Investigaciones Materno-Infantil, Obstet Gynecol Dept., San Borja-Arriarán Hospital, University of Chile and a private health center; Integramédica, división of Gynecology. All cases normalized chorionic gonadotropin. Tubal patency has been evaluated in 12 of 16 patients; 75% of the cases had patent tube in the involved side. The cumulative intrauterine pregnancy rate was 57% at 2 years with a fecundity of 2%. In the cases with a single tube, the cumulative intrauterine pregnancy rate was 40% with a 1.6% fecundity at 24 months. The ectopic pregnancy recurrence had a cumulative pregnancy rate of 48% at 2 years. The results in terms of tubal and intrauterine pregnancy obtained in this series are adequate. The ectopic pregnancy recurrence and low fecundity are probably associated to previous tubal damage. Medical treatment of ectopic pregnancy is a valid choice in selected cases with an acceptable reproductive outcome.

Embarazo ectópico: tratamiento médico / Ectopic pregnancy: medical treatment

Se presentan los resultados del tratamiento parenteral con metotrexato y manejo expectante de 32 embarazos ectópicos, en el período comprendido entre julio de 1993 y agosto de 1999. Estudio realizado en el Instituto de Investigaciones Materno-Infantil, Universidad de Chile y Servicio de Ginecología, Hospital San Borja Arriarán, junto a Integramédica, Ginecología. Veintitrés casos fueron tratados con metotrexato parenteral y 9 pacientes tuvieron manejo expectante. Los 32 casos negativizaron la gonadotrofina coriónica. No se observaron complicaciones derivadas del metotrexato, ni se requirió cirugía complementaria en ningún caso. Todas las pacientes se manejaron en forma ambulatoria. Se establecen diferencias entre las pacientes que requieren metotrexato y aquellas suceptibles de manejo expectante. La permeabilidad tubaria ha sido evaluada en 14 casos, once presentan permeable la trompa en que ocurrió el tubario y 3 pacientes mostraron obstrucción tubaria bilateral. La fertilidad y recidiva postratramiento serán evaluadas a largo plazo. El tratamiento médico del embarazo ectópico con metotrexato parenteral y el manejo expectante, constituyen alternativas válidas en casos bien seleccionados. Los resultados obtenidos en esta serie muestran una altísima efectividad, con todas las ventajas de un tratamiento ambulatorio, de bajo costo, sin complicaciones y preservación de la permeabilidad tubaria. El éxito de este tipo de manejo del embarazo ectópico depende de una estricta adhesión a los criterios de inclusión

Regulation of human luteal steroidogenesis in vitro by nitric oxide.

To evaluate the effect of nitric oxide (NO.) in human corpus luteum (CL) function, we investigated the expression and the presence of NO. synthase (NOS) in the human CL and the action of NO. on the in vitro luteal steroid production. The expression of endothelial NOS (eNOS) in early, mid-, and late CL was assessed by reverse transcriptase polymerase chain reaction (RT-PCR) and the immunohistochemical study was performed in human CL histological sections by using monoclonal antibodies (MAbs) against the distinct NOS isoforms. In addition, seven human mid-CLs were enzymatically dispersed, and the cells were cultured with NO. donor compounds. Steroid production was measured in the culture media by specific radioimmunoassay. The results show that the expression of eNOS was highly detected in mid- and early CL, and to a lesser extent, in late CL. Meanwhile, the immunohistochemical study indicated that both isoenzymes of NOS were expressed in mid-human CL, eNOS being the more abundant isoform present. On the other hand, functional studies showed that NO. donors (L-arginine [L-Arg] and sodium nitroprusside) elicited an inhibitory action on steroid synthesis, preferentially on estradiol production by the luteal cell cultures (p < 0.05). In conclusion, the NO-NOS system is present in the human CL, and it may serve as a modulator of the in vitro human luteal steroidogenesis.

Regulatory role of angiotensin II on progesterone production by cultured human granulosa cells. Expression of angiotensin II type-2 receptor.

The role of angiotensin II (AngII) in ovarian steroidogenesis is not clearly understood. In order to study its action on progesterone synthesis and to determine which receptor subtype is involve, granulosa cells obtained from women undergoing in-vitro fertilization were cultured for 2 or 4 days and then incubated in the presence of AngII (10(-7) M) with or without human chorionic gonadotrophin (HCG, 10 IU/ml) for 3 or 18 h. In cells cultured for 2 days, incubation with AngII decreased progesterone secretion by 36%, and inhibited activity of 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) by 87% (P < 0.05), although its expression was not significantly reduced. However, in cells cultured for 4 days, progesterone production was enhanced by incubation with AngII (38%), and no change was observed in 3 beta-HSD expression. Both inhibitory and stimulatory effects were dose-dependent. Progesterone secretion was increased (93%) by incubation with HCG of cells cultured for 4, but not for 2 days, and no potentiation was observed with AngII. Treatment with PD123177 completely blocked the action of AngII and decreased the HCG-stimulated secretion of progesterone by 27%. Angiotensin type-2 (AT2) receptor mRNA was expressed in cells cultured for 4 days. In conclusion, AngII showed a regulatory role in in-vitro progesterone production by human granulosa luteinized cells, modulating the activity of 3 beta-HSD. It is likely that these actions may be mediated via membrane receptors, possibly of the AT2 receptor family.

Ecografía transvaginal en pacientes posthisterectomizadas: hallazgos normales y patológicos / Transvaginal echosonography in posthysterectomized patients: normal and pathologic findings

Se presentan los resultados de la evaluación ecográfica transvaginal precoz y diferida posthisterectomía de 50 pacientes, en el período comprendido entre marzo y octubre de 1996. Estudio realizado en el Instituto de Investigaciones Materno-infantil, Universidad de Chile y Servicio de Obstetricia y Ginecología, Hospital San Borja-Arriarán. La ecografía precoz identificó correctamente la presencia o ausencia ovárica en 80 por ciento de los casos. En 21 pacientes se detectaron alteraciones ecográficas posthisterectomía, destacando 11 colecciones de cúpula vaginal. Complicaciones clínicas derivadas de la cirugía se presentaron en 12 casos, con predominio de morbilidad febril. La correlación entre la ecografía precoz y la evolución clínica posthisterectomía reveló un 31,6 por ciento de falsos positivos y un 25 por ciento de falsos negativos, con una sensibilidad del método de 75 por ciento y una especificidad de 68 por ciento. El valor predictivo positivo de la ecografía precoz fue de 42 por ciento y el valor predictivo negativo de 89 por ciento. La ecografía diferida se realizó a 42 pacientes, con correcta identificación ovárica en 78,6 por ciento de los casos, demostrando desaparición de las imágenes ecográficas precoces en 66 por ciento de las pacientes. Este examen no se correlacionó con las complicaciones clínicas postcirugía. La ecografía transvaginal puede constituir un elemento coadyuvante útil en la evaluación y manejo de la paciente posthisterectomizada que cursa con alguna complicación pélvica derivada de esta cirugía

Differential steroidogenic response of human luteal cell subpopulations.

The differential capacity for steroid synthesis of human luteal cell subpopulations was investigated in a well defined cell culture system. Corpora lutea were enzymatically dissociated, and the two cell types were obtained by a discontinuous Percoll gradient. Both cell types were cultured for 24 h with dibutyryl cAMP (1 mM), oestradiol (2.5 microM) and testosterone (1 microM). Steroid production was measured in the culture media and aromatase activity for both cell type subpopulations was also determined. Basal production of progesterone, oestradiol and testosterone was significantly greater in large cells than that in small cells (P < 0.05). Nevertheless, a greater response of small cells to several in-vitro treatments was observed. Thus, synthesis of progesterone, oestradiol and testosterone was significantly stimulated in these cells (P < 0.05) by dibutyryl cAMP. Interestingly, a 3.3-fold increase of progesterone production was also observed in the large luteal cell subpopulation. When oestradiol was added to the culture media, a 36% decrease of progesterone production (P < 0.05) by small cells was obtained, while progesterone synthesis by large cells was not significantly affected. Testosterone treatment of cells enhanced oestradiol production by both cell subtypes (P < 0.05), although the stimulatory action was greater in the small cell cultures (5.9-fold). These data indicate that the steroidogenic activity of the small cell subpopulation is highly dependent on endocrine and paracrine stimulatory mechanisms, while large cells possess a greater intrinsic steroidogenic capacity.