[Histomorphological changes in the uterus of gilts during the first 3 sexual cycles]

Histomorphological and histometric studies were conducted into the uteri of 79 gilts during their first three oestric cycles. Strong uterus growth was observed during puberty. Thicknesses of the endometrium and myometrium, height of the glandular epithelium, and the relative glandular area were significantly larger than the comparable parameters of prepuberal gilts. Another significant thickness growth was recordable from the endometrium and myometrium in the course of the first three sexual cycles. Epithelial heights, number of glandular sections in one visual field, and relative glandular area remained nearly constant between the first and third cycles, except for certain cyclic alterations. During one cycle, significant variation was recorded from the height of superficial epithelium (maximum: metoestrus), the percentual amount of glands in the total area (maximum: metoestrus to dioestrus I), and the number of glandular sections in one visual field (maximum: dioestrus I). The first sexual cycles, hence, are characterised by continued uterus growth and more stabilisation of uterus function. Gilts, therefore, should not be used for breeding until the second oestrus has taken place.