18 Mar 2013

УДК 611.9:616.3-089] (06)

T. M. Dosaev, A. N. Bekisheva,  S. T. Omarova,

 A. A.Balapanova, D. S. Baigamisova

Kazakh National Medical University after S. Asfendiyarov (Almaty)

Department of Normal Anatomy


Thus, main species peculiarities of dogs spleen as opposed to  human spleen and other laboratory animals are  following:

1) the capsule and the trabeculae is much broader  2) have a prevailing  quantity of myocytes as opposed to fibroblasts quantity,  both in the capsule and the trabelulae.

Keywords: Spleen, capsule, trabeculae



There are a number of species differences in the gross and histologic appearance of the spleen. In dogs the spleen is somewhat dumbbell shaped, while in most animals,  it is more uniform along the longitudinal axis. The spleen in dogs is able to expand to store large numbers of erythrocytes, but it is also capable of rapid contraction (1). That is why  the spleen gross appearance is quite variable, ranging from large in size and dark red to blue-black in color to smaller and lighter red. The capsule and trabeculae of dogs contains more smooth muscle (2).

The aim of this paper is to study  regularities and species peculiarities of dogs spleen architecture and to develop diagnostics and treatment methods, very important for clinical morphology and  veterinary surgery (3,4). This  problem is also important for theoretical and clinical medicine, since a dog is vastly used as a laboratory animal in research studies, which can be applied in medical practice.  Individual anatomical variability of a dog spleen as to its weight, size and shape is rather wide, what makes its shape classification difficult enough.

Mareich M. V.  [5] offers to differentiate three types of dogs spleen shape: 1) unciform, 2) lingulate and  3) transitional  (atypical).

Material and Methods

Sections of six adult mongrel dogs of both sexes were fixed in neutral formalin and embedded in paraffin. The sections were stained with azure-2 and eosin. Cross-section of  the capsule and trabeculae was measured by the ocular  micrometer,  lens used with magnification ratio 20 and the ocular has a pitch of 10.   The bulk density of fibroblasts and myoblasts in the capsule and trabeculae was studied a standard grid of LOMO microscope MBI-15.


Main  structural and functional elements of the spleen are – support and contractile apparatus, represented by the capsule and trabecular system,  and intertrabecular spaces, consisting mainly of reticulum

The capsule and trabeculae   contain dense  connective fibers  and smooth muscle.  In some cases the capsule has local irregular thickening due to elastic fibers garnetting.  In the subcapsular area individual hemorrhage foci are noticed. The hemorrhage foci erythrocytes are round and disk-shaped, some of the being  lysed (leached).   The trabeculae also contain dense fibrous connective and smooth muscle tissue.  There are thickened areas in the trabeculae due to uneven proliferation of connective and muscle tissue.

In dogs spleen like in other animals having spleens of deposit type (horses, ruminants, pigs, predators),  the capsule and trabeculae are rich with muscled tissue ejecting  the deposited blood into the bloodstream (Picture  1,2).  In the capsule and trabeculae  among connective tissue elastic fibers dominate, allowing the spleen to change its sizes  and withstand the its volume increase.  The well developed smooth muscle of the capsule in dogs spleen contain collagen and elastic fibers intermixed with fibroblasts. On the cross-section of the  dog spleen, dissected  at the moment of constriction,  the capsule and trabeculae  are markedly thicker than  those in vivo.

Morphometric  analyses of  the capsule and trabeculae  of the  dog spleen showed that  the cross-section of the capsule is considerably longer than that of the trabeculae. See Table 1.


Table 1


Cross-section (mkm)

The capsule


The trabeculae



Volume density (Vv) of  myocytes dominates over  fibroblasts Vv in both, the capsule and the trabeculae. See Table 2 below.

Table 2




Type of cells



The capsule



The trabeculae




With microscopy, it is apparent that the splenic white pulp is presented by lymphoid follicles of  various sizes, consisting of lymphoid tissue cells.  Most of  lymphoid follicles are  typically found at the adventitial coat of  the artery with numerous capillaries deviating from it.  Central arteries locate  eccentrically within lymphoid follicles.

Most of lymphoid follicles are comprised of functionally and morphologically distinct compartments:  periarteriolar B-zone ,  clear center with mantel zone and marginal zone.  The periarteriolar zone is densely populated with small lymphocytes,  macrophages and  dendritic cells in between them.    The  lymphocytes of this zone have compact hyperchromatic nuclei with narrow cytoplasm.

The clear centers  of  lymphoid follicles consist of larger cells with clear and large nuclei and relatively narrow cytoplasms, some of them being in the phase of mitosis.   The clear centers  of lymphoid follicles are surrounded by a thin lymphocytic rim of  — the mantle zone, which in some areas was barely  visible.

Follicles are surrounded by the marginal zone, containing T- and B-lymphocytes and macrophages.  It is suggested that one of the functions of the marginal zone is cooperative interaction of different cells in the immune response.   In the result of such interaction  the marginal zone B- lymphocytes , stimulated  by a proper antigen, proliferate and differentiate into  antibody-producing cells in total plasma cells and are  accumulated in cords of the red pulp. Reticular fibers form the  supporting network for the spleen follicles; at the thymus-independent area they are continuous radially and at the T-zone – along the long axis of the central artery.

According to  Schmidt E.E.et al. (6),  within the periarteriolar  lymphoid  sheath (PALS) in dogs there  are very few capillaries different from rodents where the PALS have abundant capillaries. Also in dogs, as opposed to rats, capillaries are surrounded by a cluster of macrophages, so called ellipsoids or periarterial macrophage sheaths (PAMS) (7).

The major region of the spleen is filled with the red pulp, located between  lymphoid follicles and the trabeculae, which is spaced among reticular meshwork and free cell elements, such as blood cells, plasma cells and macrophages.

The red pulp is abundantly rich with arterioles, capillaries and  thin venous sinuses, which contain lymphocytes, macrophages and erythrocytes. Sinuses are mainly extended and filled with blood.

Species variation in the structure and morphology of the venous sinuses allows to classify  spleens into two groups,  sinusal spleens and nonsinusal spleens.  In dogs  the  sinusal spleen is found. (8). The red pulp is abundantly rich with sinuses in the area adjacent to the marginal zone of lymphoid follicles, where numerous anastomoses are formed.  The number of venous sinuses in dogs spleen is greater than that of other laboratory ruminants.  In cavity of particularly broad sinuses there are lymphocytes, macrophages, leukocytes  and erythrocytes. Such sinuses are called “working” sinuses,  temporarily  isolated from the bloodstream.

Conclusions: Thus, main species peculiarities of dogs spleen as opposed to  human spleen and other laboratory animals are  following:

1) the capsule and the trabeculae is much broader;  2) have a prevailing  quantity of myocytes as opposed to fibroblasts quantity,  both in the capsule and the trabelulae; 3) have a well expressed venous sinuses making numerous anastomoses;  4) dogs spleen have very few capillaries within PALS;  5) dogs spleen have abundant  well expressed capillaries within PAMS.


1       Valli V.E., McGrath J.P., Chu I. Hematopoietic system//Handbook of Toxicologic Patology.-2002.-2.- P. 647-649

2       Cesta M.F. Normal structure, function and histology of the spleen//Toxicologic Pathology.-2006.-5.-P.-455-465

3       Vishnevskaya  T. Y. , Ilgeev S. T.  Dogs spleen and its arteries//Journal of Orenburg State Agriculture University. — 2004.- V.4.-4-1.-P.-150-151

4       Kuzmicheva E. V. Structural and functional peculiarities in  Canidae//Morphology .-2008.-№2.-P.-72-75

5       Mareich M. V.  Experiments on  rational reasons for dogs splenography // Abstract of thesis .-2005.- Krasnodar

6       6.Schmidt E.E., MacDonald I.C., Groom A.C. Comparative aspects of splenic microcirculatority pathways in mammals: the region bordering the white pulp//Scanning Microsc.-1993.-7.-613-628

7       7.Blue J., Weiss L. Electron microscopy of the red pulp of the dog spleen including vascular arrangements, periarterial macrophage sheaths (ellipsoids), and the contractile, innervated reticular meshwork//Am. J. Anat.-1981.-161.-189-218

8       8.Schmidt E.E., MacDonald I.C., Groom A.C. Microcirculation in mouse spleen (nonsinusal) studied by means of corrosion casts//J. Morphology.-1985.-186.-P.-17-29






Picture  1 — Cross-section of the capsule of the dog spleen. Azure-2 and eosin . х 400.


Picture  2 — Cross-section of the dog spleen.  Numerous  broad trabeculae within the connective tissue.

Azure-2 and eosin . х 400.


Резюме:  Методами морфометрии и стереологии установлено, что основными отличительными особенностями селезенки собак от селезенки человека и других лабораторных животных является: 1) значительные по ширине капсула и трабекулы 2) существенное преобладание количества миоцитов над фибробластами в капсуле и трабекулах.

Ключевые слова: Селезенка, капсула, трабекулы


Түйін: Морфометрия мен стереология тәсілдерімен анықталған, иттер көкбауырының басты ерекше өзгешіліктерді мынандай:

1) капсуламен трабекулалардың едәуір кең болуы 2) миоциттердің көлемдік тыныздығының капсула мен трабекулардағы фибробластардың көлемдік тығыздығнан елеулі басым болуы.

Түйіді сөздер: Көкбауыр, көкбауырдың қапшығы, трабекулар






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