Gross anatomical and histomorphometric characteristics of the oviduct and uterus during the pubertal transition in sheep

Cross anatomical and histometric characteristics of oviducts and uteri were evaluated during the pubertal transition in ewe lambs. Lambs were hysterec tomized prepubertally (PP; n = 10) or 26 +/- 2 h after onset of first (FE; n = 13) or third estrus (TE; n = 12), or estrus in mature pluriparous ewes (ME; n = 4). Gross characteristics included diameters, lengths, and weights of oviducts; diameters of uterine cornua; and weights of uteri. Histometri c characteristics of ampullae, isthmi, and uterine cornua included epitheli al cell volume, total luminal surface area, and total number of cells per a mpulla or isthmus and area of the muscularis. Side of the reproductive trac t did not affect (P > 0.10) any gross or histometric characteristic. Gross uterine characteristics increased (P < 0.05) dramatically between PP ewes a nd FE ewes, and then increased (P < 0.05) to a lesser degree between FE and TE ewes, and again (P < 0.05) between TE and ME ewes. Histological charact eristics of uteri followed a similar developmental pattern: large changes ( P < 0.05) between PP and FE ewes, slight increases between FE and TE ewes, and no change (P > 0.10) between TE and ME ewes. Oviductal weight and lengt h showed little change (P > 0.10) at puberty or by third estrus, but they w ere greater (P < 0.05) in ME ewes than in the other groups. The diameters o f ampullae increased (P < 0.05) at puberty, showed no change between FE and TE ewes, and were greatest (P < 0.05) in mature ewes. These changes seemed to be due to increases (P < 0.05) in mucosal cell height and muscularis ar ea at puberty, and to muscularis area and submucosal thickness between TE a nd ME ewes. The surface area of the ampullae increased (P < 0.05) at pubert y or by third estrus in a linear manner between PP, FE, TE, and ME ewes. Th e diameters of isthmi did not change (P > 0.10) at puberty but increased (P < 0.05) between FE and TE, and were greatest (P < 0.05) in ME ewes. The hi stological characteristics of isthmi followed the pattern observed in the a mpullae. However, the surface area of the isthmi showed no change (P > 0.10 ) at puberty or by third estrus and was largest (P < 0.05) in ME ewes. Resu lts of this study indicate that gross morphological characteristics of uter i and oviducts increase at puberty with either slight increases or changes after two estrous cycles. This relationship is also reflected by histologic al characteristics of these organs during the pubertal transition of sheep.