湖羊胎儿期与生后期的卵巢发育

OVARIAN DEVELOPMENT OF THE HU LAMBS DURING THE FOETAL AND POST-NATAL STAGES

本试验对湖羊胎儿期与生后期卵巢的发育进行了系统观测。结果表明:45天胎儿即初步形成卵巢,胎儿期卵巢生长较稳定;75天胎龄卵巢出现大量性细胞索和性细胞团;95天时卵巢分化为皮质区和髓质区,发生大量卵母细胞和原始卵泡;130天胎龄完成卵巢主要结构,分区较清楚,皮质区厚度明显减少,开始产生次级卵泡。试验证明,湖羊生后4月龄前,卵巢发育与活重关系较大,之后无直接关系。生后至六月龄,存在卵母细胞由发生到衰退的全过程,各月龄卵母细胞数基本恒定,但在前期(幼年)卵母细胞出现时多时少的现象。卵母细胞发育与所在部位有关,与卵泡生长密切相关。生后各月龄次级卵泡生长下,卵泡直径出现时大时小的现象。成熟卵泡只有直径达最大(>4毫米)且卵泡壁变薄时才出现排卵。各时期卵泡均有闭锁现象。出生后,卵巢纤维膜明显增厚,卵巢实质部分由胎儿期两个区分化为皮质区、卵泡区和髓质区。

Systematic anatomical and histological observation were made of development of the ovary, both in the foetal and post-natal stages, of the Hulambs. Results showed that ovaries were first formed by the 45th day.of foetus. and foetal growth of ovaries was relatively stable. Large numbers oi s exual cords and cell groups were observed in the ovaries by the 75th day of foetus. Ovarian differentiation into the cortical and medullary zones started from the. 95th clay of foetus,and large numbers of oocytes and primary follicles was developed. By the 130th day of foetal age, relatively clearly differentiated zones appeared, and thickness of the cortical zone obviously decreased. The production of secondary follicles started, The postnatal development of ovary was more related with the live weight of the animal during the first 4 months of the Hu-lamb. From birth to 6 month old, the whole process of evolution of the. oocytes from genesis to senility appeared, The numbers of oocytes evolved per month was basically stable. The development of oocytes was related with its position in the ovary, and was closely correlated with the growth of follicles, It was only when mature follicles reached their largest diameter ( about 4 mm) that ovulation occured. Follicles of different stages could all showed a state of atresia. The ovary differentiated from the two zones in the foetal stage now to three zones, i. e. the cortical, medullary, and the follicular zones.