Timing of spermatogenesis, chromosomes and sex determination of Amblyomma variegatum and A. Lepidum (Acari: Ixodidae)

✍ Scribed by M. Wysoki; H. R. Bolland

• Book ID: 104630400
• Publisher: Springer Netherlands
• Year: 1979
• Tongue: English
• Weight: 709 KB
• Volume: 50
• Category: Article
• ISSN: 0016-6707
• DOI: 10.1007/bf00122681

✦ Synopsis

Development of testes, course of spermatogenesis and chromosomes of Amblyomma variegatum and Amblyomma lepidum were studied. Development of the testes and progress of spermatogenesis are dependent on time of attachment to the host. Testes of A. variegatum double in length and width, those of A. lepidum almost triple in length, double in width in the distal part and remain near the same size at the proximal part. Males of A. variegaturn, examined at 24 hr. intervals, show meiotic divisions after 120 hrs and elongated spermatids in seminal vesicles after 240 hrs. The latter process occurs in A. lepidum 48 hrs later.

Both species have an XX/XO sex determination system; embryonic female tissue contains 22 chromosomes including 2 sex chromosomes, while male tissue contains only 21 chromosomes with one sex chromosome. Ten autosomal bivalents and one sex univalent are apparently present in males of both species. Surprisingly, 11 chromosomes were observed in embryonic tissue from a single batch of eggs ofA. variegatum .