ISSN:
0003-276X
Keywords:
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Medicine
Notes:
Gametogenesis and ovarian development were examined by means of histologic, cytologic and radioisotopic techniques in porcine ovaries of ages ranging from 13 days post coitum (PC) to birth (114 days PC). Limited observations were made in postnatal ovaries (birth to 130 days post partum).Primordial germ cells were noted at 18 days PC in the region of the germinal ridge (border of mesonephros) seven days prior to its formation (24-25 days).Meiosis began as early as day 40 in some cases and was a characteristic of most ovaries by day 50.Diplotene, the resting stage of porcine oocytes, first appeared at 50 days PC and 99% of all germ cells were at diplotene by 20 days post partum. Both the paucity of oogonia and absence of oogonial mitoses at day 100 PC signaled the end of oogenesis.The number of germ cells increased dramatically from the 5,000 seen at 20 days PC to a peak of 1,100,000 at 50 days. Subsequently, germinal mitotic activity decreased and necrosis of germ cells concurrently increased, resulting in a population of approximately 500,000 germ cells at birth.The injection of tritiated thymidine into fetuses of varying ages revealed that in the pig the definitive stock of oocytes arises from the prenatal period prior to day 100 with the 70-day PC-period being the major contributor.
Additional Material:
1 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/ar.1091610105
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