Oviducal glands throughout the gonad development stages: a case study of Octopus mimus (Cephalopoda)

ABSTRACT

The oviducal glands (ODG) play a crucial role in octopus reproduction. Herein, structural changes of each section of the ODG of Octopus mimus are described histologically throughout the gonad development stages (GDS). To do this, the epithelial height, stereociliated or non-stereociliated epithelium, nucleus type (pycnotic or non-pycnotic), epithelial secretions and the value range of the macroscopic maturity index (MaMI), which directly involves ODG status, were measured. The ODG are internally constituted of two glandular units (central and peripheral glands) and one set of receptacles (the spermathecae). High epithelia (40 to 80 μm) were observed in both gland units during periods with low MaMI values (< 0.1) corresponding to III-mature and IV-pre-spawning. The stereociliated epithelium was only apparent in II-maturing and III-mature in both gland units. The nuclei were noticeably pycnotic in the central gland during III-mature, IV-pre-spawning and V-spawning, but pycnotic in the peripheral gland only during VI-depletion. The epithelium was disorganised during VI-depletion, while sulphated acid mucin was only present during III-mature in the central gland. The epithelium transformations during the GDS are related to the functions of the gland units and to their multiple secretions. The ODG histology complements the GDS and provides better reproductive status assessment.

KEYWORDS:

• Central gland
• epithelium
• female reproductive system
• maturity index
• octopods
• peripheral gland
• reproductive status
• seminal receptacle
• spermatheca
• sperm storage

Acknowledgements

This paper is part of the ‘TempOxMar’ collaboration research net (Evaluacion de los efectos de la temperatura y el oxigeno disuelto en poblaciones de organismos bentonicos marinos de interes pesquero, ecologico y acuicola) organised by Universidad Nacional Autonoma de Mexico (UNAM) and supported by Direccion General de Internacionalizacion-UNAM. A. Olivares is grateful for the sabbatical year (2015–2016) provided by Universidad de Antofagasta, Chile, during which this work was developed. O. H. Avila-Poveda is commissioned as CONACYT Research Fellow/UAS-FACIMAR (project No. 2137) and participated as a member of the academic group ‘Manejo de Recursos Pesqueros UAS-CA-132, UAS-FACIMAR’ accredited to ‘TempOxMar’ and obtained research residency at UNAM under the Annual Program of Academic Cooperation UAS-UNAM (2016-NI-0036A001P001/02/03) during which this paper was prepared. This manuscript has been improved considerably by comments and suggestions from two anonymous referees, but special thanks go to Chingis M. Nigmatullin and to editors Don Colgan and Doris Shearman.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Alberto Olivares http://orcid.org/0000-0003-3949-5955

Omar Hernando Avila-Poveda http://orcid.org/0000-0002-4411-0602

Carlos Rosas http://orcid.org/0000-0002-1301-7368

Additional information

Funding

This research was partially supported by Project PAPIIT IN 219116 to C. Rosas and by the grant SNI-CONACYT/2012-2014/2015-2017 and the project PROFAPI2014/023 both to Avila-Poveda OH.