关键词: 真间性猪 , SRY , 细胞遗传 , 解剖 , 病理

Abstract: 【Objective】 The morphological, anatomical, cytogenetical and histopathological study in a true hermaphrodite pig was conducted, which aimed at elucidating the basis of genetics and reproductive development, optimizing germplasm resources for pig production. 【Method】 A large white hermaphrodite pig at five months age was used as the experimental group, versus three littermate normal male and female pigs were used as control group. The morphology of external and internal reproductive organs was examined. SRY gene was tested by PCR. Karyotype analysis was performed on metaphases obtained from conventional peripheral blood lymphocyte cultures, and was G banded and C banded. Venous sex hormones including testosterone (T), estradiol (E2), luteinizing hormone (LH), follicle-stimulating hormone (FSH), progesterone (PRG) and prolactin (PRL) were tested using radioimmunoassay. Gonads (2 cm×2 cm) were fixed with 10% neutral formaldehyde, routinely prepared as conventional paraffine sections, and then stained with haematoxylin and eosin (HE stain). The histological sections were observed and documented in light microscope. Hypothalamus and pituitary (2 mm×2 mm) were fixed with 2.5% glutaraldehyde, and ultra structure analysis was observed under the electron microscopic sections. 【Result】 The external genitals had female phenotype with an enlarged clitoris, the anus was joined with the vulva and a testis with well-developed scrotum was on the left in the hermaphrodite pig. In the hermaphrodite pig and female pigs, the diploid chromosome number was 38, XX, karyotype was 10sm+4st+12m+12t, and SRY gene was negative. No differences were found in G-banding pattern and most C-bandings with round pattern were occurred on chromosomes 1, 3, 4, 6, 8, 9, 10, 13, 14 and 16. The chromosome relative length and the arm ratio showed no significant difference (P＞0.05) between the experimental group and the female pigs. The values of T and E2 in hermaphrodite pig were at middle level compared with that in the normal male and the female pigs, but LH, FSH, PRG and PRL were relatively higher, and the ratio of LH/FSH was obviously lower than that in the female pigs. After dissection the hermaphrodite pig, the gonads were shown both ovotestes, the left one with an epididymis, showing the regressive uterine body, uterine horns and vagina. A phallus was hidden in clitoris. Ovotestis was mixed with testis and ovary, showing regressive columnar epithelial cells, normal leydig cells, no spermatogonium and its debris. Epididymis was observed with normal pseudostratified ciliated columnar epithelium cells and no spermatozoal content or cell debris in the lumen. Endometrium was shown degeneration of endometrial lining combination with some of the normal endometrial glands. Secretory cells of hypothalamus and pituitary gland were more developed in the experiment group than that in the control group. Gonadotropin-releasing hormone (GnRH) neures were shown large nucleus, increased and fused organelle. Pituitary was observed mainly gonadotroph, of which quantity was increased and secretory granules were with different sizes in the hermaphrodite pig than that in the normal pigs. The quantity of lactotrophs and the electron density of secretory granules was larger in hermaphrodite pig than that in the female pigs. 【Conclusion】 These results indicated that the intersex pig belongs to a true hermaphrodite pig with no chromosome translocation, sex hormone disturbance and no breeding value.

Key words: true hermaphrodite pig , SRY , cytogenetic , anatomy , pathology