Heifer with an XY karyotype
Keywords: XY, heifer, bovine, infertility, karyotype, Sry
A heifer was examined because she had not shown signs of estrus although she was significantly larger than normal, cycling, age-matched herd mates.
Image size: 1203 x 656 px
On transrectal examination, the genital tract was difficult to define but a cervix and small ovaries were detected. The presence of a vagina and cervix excluded the possibility of freemartinism. Cultures of skin fibroblasts and lymphocytes revealed a homogeneous population of X-Y bearing cells i.e. this animal was genetically a male. It was not possible to determine the Sry status of this animal because suitable primers for the Sry sequence were not available to us at that time (2001).
The animal was donated for further study. The tract was smaller than that of a heifer but a uterus with two horns and a body, a cervix and a vagina was present. The ovaries measured approximately 2.5 x 1 x 1 cm but were firm, wrinkled and devoid of any obvious follicles.
Image size: 1203 x 808 px
A close up view of the right ovary:
Image size 1604 x 908px
On histological examination o the ovaries, there was no evidence of any primordial follicles (oocytes) but a mass of swirling fibrous interstitial tissue contained "islands" of cells.
Image size: 4080 x 3072 px
Examination on high-power did not lead to additional clarification as to the nature of these structures.
Image size: 3000 x 1987 px
Because of the presence of an intact Müllerian system (the uterus, cervix and cranial vagina) in this animal, it is unlikely that there were Sertoli cell components in the gonads. Sertoli cells are a source of anti Müllerian hormone and inhibin, two closely related hormones that actively suppress the formation of the Müllerian system in the fetus. Therefore it is tempting to suggest that the islands of cells were abortive attempts to form a follicles, in the absence of oocytes.
