Sexual determination and differentiation during embryonic and fetal development of New Zealand rabbit females / Determinación y diferenciación sexual durante el desarrollo embrionario y fetal de conejos hembras de Nueva Zelanda

The aim of this study was to know the embryonic and fetal development of the female rabbit genital system (Oryctolagus cuniculus), describing its main phases and the moment of sexual differentiation. Eleven pregnant New Zealand female rabbits were used in different gestational phases. The day of coitus was determined as day 0. For each stage a minimum of two animals was considered. The samples were obtained every two days from the ninth day post-coitus (dpc) until the 28th dpc. The gestational period was divided in two: animals with undifferentiated sex (group 1) and animals with differentiated sex (group 2). The ages of embryos and fetuses were estimated through the crown-rump method. Subsequently, embryos and fetuses were dissected, fixed and processed to be embedded in paraffin (Histosec). The histological analysis was performed on sections stained with hematoxylin and eosin. Immunohistochemical analysis to determine sexual differentiation was performed on samples from the 16th, 18th and 28th dpc. Desert Hedgehog (Dhh) and Indian Hedgehog (Ihh) primary antibodies, respectively, were used to identify cells of the male and female germinal epithelium. The immunohistochemical results showed that at the 16th dpc, female sexual differentiation was evident, since positive expression of the Ihh protein was observed. Sexual differentiation was obtained through histological analysis on the 18th dpc and through anatomical observation of the external genitalia on the 24th dpc. Knowing the characteristics of the embryonic and fetal development of the female rabbit genital system as well as the moment of sexual differentiation make it possible to establish bases for future research that address the physiology and pathology of these organs. Thus, any alteration in the chain of events of sexual determination and differentiation must search for an explanation from the knowledge of the possible normal mechanisms affected.

El objetivo de esta investigación fue conocer el desarrollo embrionario y fetal del sistema genital femenino de conejo (Oryctolagus cuniculus), describiendo sus principales fases y el momento de la diferenciación sexual. Se utilizaron 11 conejos hembras gestantes neozelandesas, en diferentes fases gestacionales. El día del coito se determinó como día 0. Para cada etapa fue considerado un mínimos de dos animales. Las muestras fueron obtenidas cada dos días, a partir del noveno día post-coito (dpc) hasta el 28 dpc. El periodo gestacional fue dividido en dos: animales con sexo indiferenciado (grupo 1) y, animales con sexo diferenciado (grupo 2). Las edades de los embriones y los fetos fueron estimadas a través del método de crown-rump. Posteriormente, embriones y fetos fueron disecados, fijados y procesados para su inclusión en parafina (Histosec). El análisis histológico se realizó en secciones teñidas con Hematoxilina y Eosina. El análisis inmunohistoquímico para determinar la diferenciación sexual fue realizado en muestras de 16, 18 y 28 dpc. Para identificar células del epitelio germinativo masculino y feminino se utilizaron los anticuerpos primarios Desert Hedgehog (Dhh) e Indian Hedgehog (Ihh), respectivamente. Los resultados inmunohistoquímicos mostraron que a los 16 dpc se evidenció diferenciación sexual femenina, ya que se observó expresión positiva de la proteína Ihh. La diferenciación sexual, a través del análisis histológico fue obtenida a los 18 dpc y a través de la observación anatómica de los genitales externos a los 24 dpc. Conocer las características del desarrollo embrionario y fetal del sistema genital femenino de conejo, así como, el momento de la diferenciación sexual, permiten sentar bases para futuras investigaciones que aborden la fisiología y patología de estos órganos. Así, cualquier alteración en la cadena de eventos de la determinación y diferenciación sexual deberá buscar una explicación a partir del conocimiento de los posibles mecanismos normales afectados.

Qualidade seminal e morfometria testicular de coelhos (Oryctolagus cuniculus) suplementados com geleia real / Seminal quality and testicular morphometry of rabbits (Oryctolagus cuniculus) supplemented with royal jelly

Objetivou-se avaliar o efeito da geleia real na qualidade seminal e na morfometria testicular de coelhos. Quatorze coelhos adultos da raça Nova Zelândia foram distribuídos em três grupos: com administração diária de 1mL de água, via oral (SG); administração diária de 0,5mg (0,5G) de geleia real diluída em 1mL de água, via oral; e administração diária de 1,0mL (1,0G) de geleia real diluída em 1mL de água, via oral. O fornecimento de geleia real foi iniciado 30 dias antes das coletas de sêmen, permanecendo durante todo o período de coleta, totalizando 90 dias. Utilizou-se o método da vagina artificial para coleta de sêmen. Foram avaliados os parâmetros físicos e morfológicos do sêmen e os parâmetros de morfometria testicular. Houve diferença no volume seminal do 0,5G (0,54±0,22) em relação ao SG (0,39±0,13) e ao 1,0G (0,30±0,09) (P<0,05). Para os grupos SG, 0,5G e 1,0G, não houve diferença (P>0,05) para turbilhonamento espermático, concentração espermática, motilidade progressiva e vigor espermático. Os defeitos maiores no grupo 0,5G (8,52±3,26) foram menores do que nos grupos SG (14,09±4,26) e 1,0G (16,1±3,95) (P<0,05). Não houve diferença entre os defeitos menores e os defeitos totais (P>0,05). Os pesos corporal, testicular, epididimário e o índice gonadossomático não diferiram entre os grupos (P>0,05). A ingestão diária de 0,5mg de geleia real apresentou efeitos positivos na morfologia espermática de coelhos.

A trial was carried out to evaluate the effects of royal jelly on the seminal quality and testicular morphometry of rabbits. Fourteen mature rabbits of New Zealand breed were distributed between three groups. The first group was supplied with 1mL of water only (SG), the second group was supplied with 0.5mg of royal jelly diluted in 1mL of water (0.5G), and the third group was supplied with 1mg of royal jelly also diluted in 1mL of water (1.0G). The royal jelly supply started 30 days before semen collection and lasted the entire experimental period. An artificial vagina was used to collect the rabbits' semen. Physical and morphological parameters in the semen and the testicular morphometry were evaluated. Differences were found on the seminal volume in group 0.5G(0,54±0,22) in relation to SG (0,39±0,13) and 1.0G (0,30±0,09) groups (P<0.05). For SG, 0.5G and 1.0G groups, no differences (P>0.05) were found in sperm concentration, gross motility, individual motility and vigor. The total of primary defects in group 0.5G (8,52±3,26) was lower than in groups SG (14,09±4,2) and 1.0G (16,1±3,95) (P<0.05). No significant difference was found between secondary defects and the total defects on the semen (P>0.05). Body, testicular and epididymal weights did not differ between groups, as well to the gonadosomatic index (P>0.05). The ingestion of royal jelly produced positive results on the seminal production of males.

Quantitative and topographic analysis of sulphur in the zona pellucida from mouse, hamster and rabbit oocytes

Mediante la técnica del microanálisis de rayos X, se investigó la cantidad y distribución del azufre en la zona pelúcida de los ovocitos de ratón, hamster y conejo. La cantidad de azufre varía entre 2853 y 10178 mmol/Kg de peso seco. La cantidad más alta de azufre se encontró en los ovocitos de hamster y la más baja en los ovocitos de conejo; siendo la cantidad encontrada en los ovocitos de ratón, intermedia entre ambas. Se detectó una disminución gradual del azufre desde la región interna hacia la región externa de la zona pelúcida, en los ovocitos de ratón y conejo. Esto es coincidente con las asimetrías morfológica y/o bioquímica descritas para la zona pelúcida de estas especies. Aunque se han descrito asimetrías bioquímica y funcional en la zona pelúcida de los ovocitos de hamster, en el presente análisis no se detectó una distribución asimétrica del azufre. Sin embargo, resultó evidente una estratificación de este elemento en la zona pelúcida de los ovocitos de hamster

Pre-natal development of the choroid plexus in rabbit

Development of the choroid plexus of the lateral ventricle in rabbit was studied by histological paraffin sections. The choroid plexus is first observed as an invagination from the medial wall of the ventricle at the ninth day of gestation. From the age of 10 days to the age of 13 days prenatally the choroid epithelium is pseudostratified columnar. By the age of 14 days the choroid epithelium starts to present changes from pseudostratified columnar to simple columnar cells. Dark and light can be detected and a large number of metachromatically stained cytoplasmic inclusions at the basal pole can be detected from the age of 16 days prenatally

Pre-natal development of the lens in rabbit

From this study it could be concluded that: 1. The lens placode could be detected on the 6th day of gestation. 2. The lens vesicle was completely formed by the 8th day of gestation. 3. Formation of the lens fibers started in the central cells of the posterior epithelium as their nuclei were thrown forwards to form the primitive lens fibers. 4. The newly formed lens fibers from the equatorial cells were laid down concentrically round the filled - in lens vesicle

Differentiation of the cortical plate in the cerebral cortex of rabbit

The cortical plate could be distinguished at the age of 16 days prenatally. Differentiation of the cortical plate occurred with advancement of age leading to the formation of the different layers of the cortex by the following sequence of changes.a-Differentiation began and proceeded most rapidly after the arrival of neuroblasts to the other part of the cortical plate b-Somata of old elements appeared to move to inner levels of the cortical c-The terminal denderitic arbors of pyramidal cells remained, in the marginal lamina while the apical processes grew progressively longer

Origin of the cortical plate of the cerebral cortex of rabbit

This sutdy revealed that: 1. The cortical plate could be distinguished at the age of the 16th day prenatally in rabbit embryo. 2. Formation of the cortical plate was due to continuous migratory process of neuroblasts from the neuro-epithelial cells in the matrix lamina