Author/Editor		Molenaar, GJ
Title		Anatomical, developmental and immunocytochemical aspects of the porcine hypothalamo-hypophyseal-gonadal axis
Type		članek
Source		Zb Vet Fak Univ Ljublj
Vol. and No.		Letnik 30, št. 1
Publication year		1993
Volume		str. 81-8
Language		eng
Abstract		Porcine sexual differentiation during early development differs from that in the rat by the presence of two instead of a single testosterone (T) peak. The first peak occurs at the age of 7-8 weeks of fetal life and appears to be related to the differentiation of the male gonads. The second peak occurs nennatally and is perhaps the homologue of the single T peak in rodents. If this hypothesis is correct this would implicate that this T peak is responsible for the sexual differentiation at the hypothalamic level. Therefore, the detailed anatomy of the GnRH system has been studied as well as its morphogenesis. Before immunohistochemistry can be applied to the porcine hypothalamus special and elaborate precautions have to be taken in order to avoid false positive labelling. This is caused by the high affinity of certain hypothalamic cell groups for the Fc fragments of rabbit irnmunoglobulins. It appears that three cell groups can be distinguished two of them i.e. the septo-preoptic and tuberal groups, have projections into the neurohemal organs. The number of positively reacting cells is inversely related to the mean plasma LH level in the septo-preoptic cell group but not in the tuberal cell group. The effect of the neonatal T peak on hypothalamic differentiation has been studied after experiments involving testosterone depletion and suppletion. The cytoarchitecture of the alleged homologue of the human SDN-MPOA has been studied in the male and female controls and was compared with that in experimental animals which had been neonatally gonadectomized and/or had received T implants. The animals were sacrificed at the age of 38 weeks. Sexual dimorphism appeared to become apparent no sooner than at two years of age. Moreover, the nucleus consisted of vasopressin and oxytocin contaimng cells unlike the human or rodent homologue.
Descriptors		HYPOTHALAMUS SEX CHARACTERISTICS TESTOSTERONE LH ANIMALS, DOMESTIC SWINE GONADORELIN