Stereological comparison of smooth muscle, collagen, and elastic fibers of the clitoris and glans penis in young adults.

OBJECTIVE: To compare the collagen, elastic fibers, and smooth muscle content of the clitoris and the glans penis in young adults. MATERIALS AND METHODS: The clitoris and the glans penis of six women and six men (mean age 25±3) who died as a result of accidents were excised. The samples were placed under a formaldehyde solution and histologically processed. Masson's trichrome and Weigert's resorcin-fuchsin stain was used to highlight the elastic fibers, smooth muscle, and collagen. Stereological analysis was conducted in 5 random fields of 5 slides for each sample. For statistical analysis, the unpaired t-test was used to compare values between groups, and a value of P<0.05 was considered as significant for all analyses. RESULTS: Stereology revealed a mean smooth muscle content of 35.84±6.46% and 31.64±4.74% for the clitoris and glans penis, respectively, while it also revealed collagen content of 26.11±7.41% and 28.44±3.55% and elastic fibers content of 24.12±4.34% and 30.97±6.13% for the clitoris and glans penis, respectively. The statistical analysis showed no significant differences between them. CONCLUSION: Regardless of anatomical differences, the volumetric density of collagen, elastic fibers, and smooth muscle were similar for the clitoris and glans penis in young adults, a feature possibly explained by their embryology.

Acute blockade of nitric oxide synthesis induces disorganization and amplifies lesion-induced plasticity in the rat retinotectal projection.

In the rat visual system, the uncrossed retinotectal projection undergoes a topographical refinement within the first two postnatal weeks. We have studied the role of nitric oxide (NO), a retrograde messenger which couples pre- and postsynaptic activation, in the development of the uncrossed retinotectal projection and in the plasticity of this pathway as a result of a restricted retinal lesion in the opposite eye. During development, maximal nitric oxide synthase (NOS) activity was observed in homogenates of tectal tissue at postnatal day 5 (PND 5), followed by a two-step decrease at the end of the topographical fine tuning period (PND 21) and the adult stage (PND 42). We also tested the effects of an acute in vivo blockade of NOS during the development of both animals that had not been operated on, and lesioned animals. Animals ranging from PND 4 to PND 42 were treated either with the NOS inhibitor, L-nitro-arginine (Narg 50 mg/kg ip.) or vehicle (NaCl 0.9%) during 4 days (from PND 4-7 or PND 9-12) or 8 days (from PND 20-27 or PND 34-41). Reduction of NOS activity induced sprouting of the ipsilateral pathway up to the second postnatal week in the animals that had not been operated on. Rats that had been operated on, however, showed an amplification of the lesion-induced plasticity up to the fourth postnatal week under NOS blockade. The data suggest that NO plays a role in the stabilization of retinotectal synapses during the critical period of topographic refinement, and indicate that an acute blockade of retrograde signals enables plastic rearrangements in the visual system within this time window.

The use of high resolution banding in comparative cytogenetics: comparison between man and Lagothrix lagotricha (Cebidae).

New techniques for obtaining high resolution banding are used in comparative cytogenetics. They make possible a direct comparison of the chromosomes of two distantly related primates, man and Lagothrix lagotricha (Platyrrhine). For many chromosomes, the homoeologies of banding are surprisingly clear. These new results strongly strengthen the interpretations proposed with the use of more conventional banding techniques.

[Cytogenetic study of six species or sub-species of mangabeys monkeys (Papiinae, Cercopithecidae) (author's transl)]. / Etude cytogénétique de six espèces ou sous-espèces de mangabeys (Papiinae, Cercopithecidae).

Chromosome banding patterns of six Mangabey species or sub-species are studied and compared. By comparison with the other Papiinae previously studied (Papio and Macaca) Lophocebus albigena and L. aterrimus possess very similar karyotypes, differing a most by a pericentric inversion of the Y chromosome. The other four, Cercocebus torquatus torquatus, C. t. fuliginosus, C. galeritus galeritus and C. g. chrysogaster differ by a complex rearrangement of chromosome no. 10 and by acquisition of heterochromatin on chromosome no 12. No difference was detected nor between the two Lophocebus nor between the four Cercocebus. Cytogenetic criteria age thus in agreement with the morphological, immunological and hematological data, separating the two genuses, and placing Lophocebus closer to the Papio and Macaca than to Cercocebus.

[Use of BrdU in the study of cell cycle in normal and abnormal subjects]. / Utilisation du BrdU dans l'étude du cycle cellulaire de sujets normaux et anormaux

Chromosome modifications induced by BrdU allow a study of the cell division cycle during, at least, three consecutive generations. Among normal lymphocytes, the cell cycle varies in duration, but for the majority of cells, is a little shorter than twenty hours. In trisomy 21 individuals, the mean cell cycle is shorter, around 16 hours. In Fanconi's anemia, the cell cycle is slowed down and its duration is approximatively twice that of normal individuals. Endoreduplicating cells seem to have the cycle of longest duration.