Sperm morphometry is the tool that confers objectivity to the morphological evaluation by accurately measuring the dimensions of the gamete and its structures. Thus, the aim of the study was to perform a morphometric characterization of the domestic cat sperm. Therefore, sperm samples were collected from twenty pairs of epididymis in a TRIS extender at 37ºC. An aliquot of the sample was used to make a smear with Rose Bengal solution, and afterwards, the morphology and morphometry were analysed. In the morphology, were quantified the percentage of normal sperm cells, morphological changes of head, midpiece and tail. In morphometry, each normal sperm cell was measured for length, width, area and perimeter of head and midpiece, tail length and total length. The parameters ellipticity, elongation, regularity and rugosity were also determined. The percentage of normal sperm was 67.21%. Of the abnormalities, the curled/folded tail, followed by the curved midpiece, abnormal shaped head and detached head were the most quantified. The sperm head presented 5.56 ± 0.01 μm and 3.10 ± 0.01 μm of length and width, respectively. The head area was 16.94 ± 0.05 μm2, while the perimeter was 16.16 ± 0.03 μm. In the derived parameters, the values were as follows: ellipticity of 1.81 ± 0.00; elongation of 21.39 ± 0.12; regularity of 0.81 ± 0.00; and rugosity of 0.14 ± 0.00. The midpiece presented length and width of 7.96 ± 0.01 μm and 0.76 ± 0.01 μm, respectively. The mean length of the sperm tail was 45.12 ± 0.06 μm, and the total cell size was 58.67 ± 0.06 μm. Thus, it was concluded that the cat sperm is an elongated cell, with high rugosity and regularity. The spermatic tail represents more than ¾ of the total length of the cell and the midpiece exceeds the length of the head.

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Recuperação e conservação de espermatozoides epididimários: Perspectivas e aplicações na espécie felina doméstica[Recovery and conservation of epididymal sperm: Prospects and applications in the domestic feline species] Resumo A recuperação e criopreservação dos espermatozoides epidídimários é uma ferramenta promissora no resgate e/ou prevenção da perda de material genético de machos valiosos ou estimados, ou mesmo, de animais em risco de extinção. A conservação destes espermatozoides na espécie felina doméstica ainda apresenta resultados conflitantes, dificultando a aplicação da biotécnica na área comercial, para animais de padrão racial desejado. Contudo, inúmeras pesquisas investigam as peculiaridades fisiológicas dos espermatozoides felinos, com o intuído de desenvolver protocolos e meios de criopreservação promissores. Assim, alguns trabalhos já reportaram sucesso na congelação dos espermatozoides epididimários de gatos, bem como, no emprego destas células em técnicas de reprodução assistida (inseminação artificial e fecundação in vitro). Portanto, o presente artigo tem como finalidade explanar os principais avanços na área da recuperação e conservação dos espermatozoides epididimários para os gatos domésticos e, enfatizar as perspectivas futuras destes trabalhos na conservação do germoplasma felino.Palavras-chave: espermatozoide felino; epidídimo; recuperação de espermatozoides; criopreservação. AbstractThe recovery and cryopreservation of epididymal sperm is a promising tool in the rescue and prevention of loss of genetic material from valuable and/or estimated males, or even animals at risk of extinction. The conservation of these gametes in the domestic feline species still presents conflicting results, hindering the application of this biotechnology in the commercial area for animals of the desired racial pattern. However, numerous studies investigate the physiological peculiarities of feline sperm with the objective of developing promising cryopreservation protocols and means. Thus, some studies have reported success in the freezing of epididymal sperm, as well as in the use of these cells in assisted reproduction techniques (artificial insemination and in vitro fertilization). Therefore, this article aims to explain the main advances in the area of recovery and conservation of epididymal sperm for domestic cats and to emphasize the future prospects of this work in the conservation of feline germplasm.