Papah M.B., Kisia S.M., Ojoo R.O., Makanya A.N., Wood C.M., Kavembe G.D., Maina J.N., Johannsson O.E., Bergman H.L., Laurent P., Chevalier C., Bianchini A., Bianchini L.F., Onyango D.W.
Dept. of Veterinary Anatomy and Physiology, University of Nairobi, 30197-00100 Nairobi, Kenya; Dept. of Biology, McMaster University, Hamilton, ON L8S 4K1, Canada; Marine Biology and Fisheries, Rosenstiel School, University of Miami, FL 33149, United States; Dept. of Range and Wildlife Sciences, South Eastern University College, 170-90200 Kitui, Kenya; Dept. of Zoology, University of Johannesburg, South Africa; Great Lakes Laboratory for Fisheries and Aquatic Sciences, Dept. of Fisheries and Oceans, Canada, Burlington, ON L7R 4A6, Canada; Dept. of Zoology and Physiology, University of Wyoming, Laramie, WY 82071, United States; Instituto de Ciências Biológicas, Universidade Federal do Rio Grande (FURG), 96201-900 Rio Grande, RS, Brazil
Papah, M.B., Dept. of Veterinary Anatomy and Physiology, University of Nairobi, 30197-00100 Nairobi, Kenya; Kisia, S.M., Dept. of Veterinary Anatomy and Physiology, University of Nairobi, 30197-00100 Nairobi, Kenya; Ojoo, R.O., Dept. of Veterinary Anatomy and Physiology, University of Nairobi, 30197-00100 Nairobi, Kenya; Makanya, A.N., Dept. of Veterinary Anatomy and Physiology, University of Nairobi, 30197-00100 Nairobi, Kenya; Wood, C.M., Dept. of Biology, McMaster University, Hamilton, ON L8S 4K1, Canada, Marine Biology and Fisheries, Rosenstiel School, University of Miami, FL 33149, United States; Kavembe, G.D., Dept. of Range and Wildlife Sciences, South Eastern University College, 170-90200 Kitui, Kenya; Maina, J.N., Dept. of Zoology, University of Johannesburg, South Africa; Johannsson, O.E., Great Lakes Laboratory for Fisheries and Aquatic Sciences, Dept. of Fisheries and Oceans, Canada, Burlington, ON L7R 4A6, Canada; Bergman, H.L., Dept. of Zoology and Physiology, University of Wyoming, Laramie, WY 82071, United States; Laurent, P., Dept. of Biology, McMaster University, Hamilton, ON L8S 4K1, Canada; Chevalier, C., Dept. of Biology, McMaster University, Hamilton, ON L8S 4K1, Canada; Bianchini, A., Instituto de Ciências Biológicas, Universidade Federal do Rio Grande (FURG), 96201-900 Rio Grande, RS, Brazil; Bianchini, L.F., Instituto de Ciências Biológicas, Universidade Federal do Rio Grande (FURG), 96201-900 Rio Grande, RS, Brazil; Onyango, D.W., Dept. of Veterinary Anatomy and Physiology, University of Nairobi, 30197-00100 Nairobi, Kenya
Spermatogenesis in Lake Magadi tilapia (Alcolapia grahami), a cichlid fish endemic to the highly alkaline and saline Lake Magadi in Kenya, was evaluated using light and transmission electron microscopy. Spermatogenesis, typified by its three major phases (spermatocytogenesis, meiosis and spermiogenesis), was demonstrated by the presence of maturational spermatogenic cells namely spermatogonia, spermatocytes, spermatids and spermatozoa. Primary spermatogonia, the largest of all the germ cells, underwent a series of mitotic divisions producing primary spermatocytes, which then entered two consecutive meiotic divisions to produce secondary spermatocytes and spermatids. Spermatids, in turn, passed through three structurally distinct developmental stages typical of type-I spermiogenesis to yield typical primitive anacrosomal spermatozoa of the externally fertilizing type (aquasperm). The spermatozoon of this fish exhibited a spheroidal head with the nucleus containing highly electron-dense chromatin globules, a midpiece containing ten ovoid mitochondria arranged in two rows and a flagellum formed by the typical 9. +. 2 microtubule axoneme. In addition, the midpiece, with no cytoplasmic sheath, appeared to end blindly distally in a lobe-like pattern around the flagellum; a feature that was unique and considered adaptive for the spermatozoon of this species to the harsh external environment. These observations show that the testis of A. grahami often undergoes active spermatogenesis despite the harsh environmental conditions to which it is exposed on a daily basis within the lake. Further, the spermiogenic features and spermatozoal ultrastructure appear to be characteristic of Cichlidae and, therefore, may be of phylogenetic significance. © 2013 Elsevier Ltd.
