| Abstract: | The ages of puberty and sexual maturity were histologically determined in 300 dogs, comprising 115 local Nigerian dogs and 185 crosses of local with exotic breeds. The ages ranged from six months to eight and a half years. The age at puberty was estimated to be seven to eight months and the age of sexual maturity to be 10 to 11 months for all the dogs, both local and exotic. Testicular and epididymal dimensions and weights, on average, increased progressively from before puberty until sexual maturity. The same trend was observed in the diameters of seminiferous tubules, the percentage of spermatogenesis and the epididymal sperm reserves. At puberty an average of 51.8 per cent of the caudal epididymal sperm cells of the local dogs had morphological defects compared with 54.5 per cent in the exotic cross breeds. The defects were mostly coiled tails and proximal cytoplasmic droplets. These defects had decreased to an average of 12.8 per cent in all breeds by the time the dogs had attained a mean age of one and a half years. In general the post-pubertal pattern of spermatogenesis in the dogs resembled that of the bull, and the ages at onset of puberty and sexual maturity fall within the range determined for exotic breeds of dogs. There were no significant differences between the local Nigerian dogs and the local cross exotic breeds in the parameters studied. |
