Journal of Morphology

One of the key innovations is the mammalian neocortex. The current view is that a neocortex firstly evolved in late Triassic Mammaliaformes. Here, we report the earliest evidence of a structure analogous to the mammalian neocortex in a late Permian therapsid.

Mandible growth from the second to the eighth postnatal week is compared between mice from wild populations of Mus musculus domesticus and mice of the C57BL/6J strain. Bone surface data not only reveals similar bone remodeling patterns and growth directions of the mandible between these wild and laboratory mice but also differences in the distribution of bone deposition fields (light gray) and bone resorption fields (dark gray), over ontogeny. Geometric morphometric analyses show similar allometric shape changes of the mandible in both groups of mice, but between-group differences in mandible size and shape especially after weaning.

Heptranchias perlo is one of the most unusual extant sharks. It has as many gill pouches as lampreys—seven pairs of them instead of five, typical to sharks. However, this is not an ancient feature but a breathing adaptation ensuring increased surface area for gas exchange. Another adaptive feature is its very tall gill slits, which allow water to come more easily out of gill pouches. With these features, even slow swimming supplies sufficient water flow through gills. Breathing due to swimming is known as ram ventilation, but ram-ventilating sharks with five gill pouches are incapable of breathing at such low speeds as Heptranchias.

We survey cuticular organs (simple pores with and without a lip carrying an undivided sensory seta) in one widely distributed freshwater species, Physocypria kraepelini. Total number of pores varies between valves and sexes, but we detected 27 pores homologous across valves and sexes. We used those pores as landmarks for a 2D geometric morphometric analysis with the aim to compare its power to detect sexual dimorphism and directional asymmetry of size and shape in this species relative to Fourier outline analysis. Two geometric morphometrics methods were congruent in the estimation of sexual dimorphism and shape directional asymmetry, but differ in the statistical evaluation of size directional asymmetry.

Migration of heart (% total body length, TL) toward head in 4 species of snakes. The migration of heart reverses direction in older individuals of Acrochordus granulatus (aquatic) and Agkistrodon conanti (ground-dwelling), but not in the aquatic Hydrophis platurus or semi-terrestrial Pantherophis obsoleta.

Comparative drawings from immature and mature ultimobranchial follicles (UBFs) in the thyroid gland of young and adult rats, respectively. In the immature form of UB-remnants, different types of cells can be observed: (a) undifferentiated peripheral cells; (b) cystic squamous cells; (c) differentiated thyroid cells; (d) follicular thyroid cells and, finally, (d) C-cells. Conversely, in mature UBF, no more differentiated thyroid cells are formed, whereas undifferentiated cells and cystic squamous cells persist at UBF-level throughout rat span life.

• Cranial suture complexity is higher in species with harder diets and/or burrowing habits.

• Sutures at the boundary of the rostral region and the cranial vault are more complex than sutures in the cranial vault itself.

• Species that inhabit open and arid regions showed more complex sutures.

• Skull size does not affect the complexity of cranial sutures.

• We found different morphological patterns even within a single suture, which may be related to the complex loadings affecting the cranium.

Structural adaptation of trematode miracidium to active host finding strategy

Subcellular distribution of intracellular calcium in different stages of spermatogenesis in zebrafish, Danio rerio was described and compared. The proportion of area covered by calcium increased significantly from early to late stages of spermatogenesis. The intracellular calcium is sequestered as deposit and unbound forms in early and late stages of spermatogenesis, respectively.