Abstrak: Kecepatan perkembangan embrio Chelonia mydas dipengaruhi oleh suhu inkubasi. Embrio yang diinkubasi pada suhu 31±1°C (SF) mencapai tahap 17 pada umur inkubasi 22-23 hari, tahap 19 pada umur inkubasi 26 hari, dan tahap 22 pada umur inkubasi 31 hari. Embrio yang diinkubasi pada suhu 26±1°C (SM) mencapai tahap tahap 17 pada umur inkubasi 39-40 hari, tahap 19 pada umur inkubasi. 45 hari, dan tahap 22 pada umur inkubasi 52-53 hari. Hasil pengamatan terhadap struktur histologis gonad embrio menunjukkan bahwa gonad embrio tahap 17, 19, dan tahap 22 telah berupa gonad indiferen. Gonad-gonad pada tahap tersebut sudah dapat dibedakan menjadi bagian korteks dan bagian medula. Bagian korteks berupa epitel selapis silindris, sedangkan bagian medula mengandung jaringan ikat dan kelompok-kelompok sel. Bakal sel kelamin ditemukan pada bagian medula dan korteks. Dengan demikian dapat disimpulkan bahwa periode TSP Chelonia mydas yang diinkubasi pada suhu 31±1°C (SF) terentang dari umur inkubasi 22 hari hingga umur inkubasi 31 hari, sedangkan periode TSP Chelonia mydas yang diinkubasi pada suhu 26±1°C (SF) terentang dari umur inkubasi 39 hari hingga umur inkubasi 53 hari.Kata kunci: Chelonia mydas, TSP, umur inkubasi, suhu feminisasi, suhu maskulinisasi Abstract: Embryonic development Rate of Chelonia mydas is affected by incubation temperature . The embryos were incubated at 31 ± 1°C ( FT ) reached embryonic stage of 17th at 22-23rd of incubation day, embryonic stage of 19th at 26th of incubation day, and embryonic stage of 22nd at 31st of incubation day. The embryos were incubated at 26 ± 1°C ( MT ) reached embryonic stage 17 th at 39-40th incubation day , embryonic stage 19 th at 45 th day of incubation , and embryonic stage 22nd at 52-53 rd incubation day. Observations on the histological structure of the gonadal embryos showed that the embryonic gonad stages 17th , 19th , and 22nd have been in indifferent stage. Gonads at this stage can be distinguished in two parts, cortex and medulla. Cortex as a layer of cylindrical epithelium, while the medulla consist of connective tissue and groups of cell. Primordial Germ Cells are found both in medulla and cortex . It can be concluded that the TSP of Chelonia mydas were incubated at 31 ± 1°C ( FT ) extended from 22nd of incubation day until the 31st of incubation day , whereas the TSP of Chelonia mydas were incubated at 26 ± 1°C (MT) extended from 39th of incubation day until the 53rd of incubation day.Key words: Chelonia mydas, TSP, feminization temperature, maskulinization temperature